Lin Yang,Chunping Wu,Yiran Zhang,Bang Xiao,Anqi Jiao,Ke Li,Ting Chen,Reggie Zhan,He Lin
A mixed potential ammonia sensor using In2O3 sensing electrode was prepared, and its sensing performance was enhanced by adjusting particle size with calcination heating rate as well as the utilization of NiCo2O4 reference electrode. It was found that the sensor with a calcination heating rate of 2 °C min−1 had the best performance, with a sensitivity of −61.27 mV decade−1 at 525 °C, and the TEM results showed that the average particle size was 70.36 nm. Furthermore, the sensor exhibited good stability against oxygen concentration fluctuation. The results also indicated that the mixed potential has a linear relationship with the logarithm of NH3 concentration, suggesting that the ammonia sensors in this study conform to the mixed potential theory. To address the issue that most ammonia sensors are susceptible to NO2 interference, NiCo2O4 was used as reference electrode to replace the Pt reference electrode, which could greatly offset the response of NO2 and improve the sensors selectivity. In summary, the developed In2O3/YSZ/NiCo2O4 sensor exhibited a great potential for NH3 monitoring in SCR systems.
Bang Xiao,Anqi Jiao,Yiran Zhang,Lin Yang,Xuteng Zhao,Chunping Wu,Dongdong Guo,Reggie Zhan,He Lin
NH 3 detection is of great significance for precise control of the SCR system. In this paper, mixed potential type ammonia sensor using LaCo 1-x Fe x O 3 sensing electrode, YSZ electrolyte, and Pt reference electrode was developed. LaCo 1-x Fe x O 3 sensing materials were made by flame spray pyrolysis technique, and Fe B-site substitution was implemented to enhance the sensing performance. It was observed that in the concentration range of 20–70 ppm at 475 °C, the sensor using LaCo 0.9 Fe 0.1 O 3 as sensing electrode exhibited the highest sensing signal and sensitivity to ammonia among the LaCo 1-x Fe x O 3 -SE sensors (x = 0, 0.05, 0.1, 0.2, 0.3). A sectional linear relationship between the response value change( Δ V ) of that sensor and the logarithm of ammonia concentration within the range of 2–15 ppm and 15–70 ppm was noticed, and the sensitivities were 17.52 and 87.22 mV/decade, respectively. Its lower detection limit reached 2 ppm at 475 °C. Its excellent sensing properties are ascribed to enriched oxygen vacancies and high electrocatalytic performance of the perovskite electrode. Moreover, the sensor exhibited good selectivity against CH 4 , CO, NO, NO 2 , and good stability against oxygen and water vapor concentration fluctuation. Besides, the sensing response to 50 ppm ammonia has been tested for 22 days and only a slight fluctuation within 7 % was observed. Furthermore, the mixed potential sensing mechanism of the sensor was discussed.
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